Oxygen Sensor question

fitz · fitz's Garage

Can any one help me? Yesterday, I finally had time to possibly change my o2 sensor but ran into a snage. I got Wayne's book which helped out enormously as to how to get to the o2 sensor but there was something different on my p-car that I didn't know how what to do. I have an '88 911 cab which has a shield around the o2 sensor. I removed a shield around the muffler and found the o2 sensor, but on the muffler there was a little shield aroung the sensor. I couldn't remove the shield because it seemed welded on and it looked like the sensor snappeed into the shield.

Has anybody come across this before? If so, how do I remove the sensor? If you all need pics, I can take some if it will help.

Any help is appreciated
Ron Fitz

ChrisBennet · ChrisBennet's Garage

The O2 sensor shield (on the ones I've seen) has two fingers that snap around the O2 sensor. It should pull right off. The cat and O2 sensor shields protect the left rear tire. That cat gets pretty hot.
-Chris

scottb · 09-22-2003, 03:52 PM

Chris is correct. There's a clip that is attached to the shield, and it snaps around the sensor. It's pretty easy to remove.

fitz · fitz's Garage

Chris and Scott,
Thanks for the replies. Just to make sure the shield is NOT welded on to the catalytic converter but will come off, is this correct? I thought I was going to have to take the car to my mechanic $$$. I'll try again this weekend when I have a chance to work on the car.

Thanks for the help...Ron Fitz

scottb · 09-22-2003, 04:38 PM

At least on my car, the shield was clipped to the sensor, and the base of the shield fit into a hole in the cat...it was NOT welded.

NY65912 · 09-22-2003, 05:11 PM

I just changed the O² sensor this weekend on my 85 911. I recommend cutting the wires off the old one and use a deep socket to remove it, it bites better than the "special" sensor socket. Install the new sensor with some antisieze compound and use the special sensor wrench if you have one. The hardest part of the job was removal. I sprayed it down with Kroil and it was still a SOB to get out, (original to car). The result was the car no longer has a rich smell and definitely a smoother running engine.

Good Luck, Mike

Wil Ferch · 09-23-2003, 08:33 AM

Use "O2 sensor safe" anti seize..if you use this stuff. Even small amounts of bad stuff or silicone will ruin your new sensor..
----Wil Ferch

fitz · fitz's Garage

Mike,
Thanks for the advice. I did buy the O2 sensor tool and was going to try to use it but I'll try your way first. Also, based on 101 project book I did get some anti seize stuff for the sensor.

Wil, I'll check to see if the anti seize again to make sure it will work ok.

Thanks for sharing your experiences with me regarding the 02 sensor. This will help me a great deal since I'm not a professional mechanic.

Ron

ChrisBennet · ChrisBennet's Garage

New O2 sensor have some sort of antiseize on the threads already I think. I would be afraid that the common silver colored (aluminum) antiseize might be worse than none at all. Anyone up on antiseize technology? Will the the aluminum stuff weld stuff together at the temps a cat sees?
totally ignorant,
Chris

BGCarrera32 · 09-23-2003, 12:19 PM

Quote:

Anyone up on antiseize technology?

Well, let me just pull down my copy of "Antiseize technology for Dummies" off the old bookcase here...

As far as welding I doubt it. I think the aluminum antiseize is good for over 1000 degrees F, and I'd be willing to bet that the plating on the threads of the sensor acts much like the antiseize would. I base this off of hearing that its not necessary on a lot of the new spark plugs to use anti-seize...I don't on my 911 and haven't had a problem yet... I'd be more worried about getting it on the sensor tip where it would never burn off.

-BG

NY65912 · 09-23-2003, 04:47 PM

Fitz. keep us posted, I'd like to know the effect of changing the sensor has on your car.

Mike

bob hodges · 09-24-2003, 04:25 AM

I have a new O2 sensor sitting on my bench in my garage and was going to replace it some time ago but during my attempt to remove the old one I discovered that it was a bit difficult to remove. That is saying it without ***@##. I am reading all the stories about removing the old sensor and I am of the opnion that it will have to have some real heat to get the old sensor out of the cat. Any thoughts??

FRED/LI · 09-24-2003, 04:43 AM

You already have a heat source at your disposal. You jackstand the left rear, remove the wheel, start the engine, run it five minutes and then remove the sensor.

fitz · fitz's Garage

Wow wasn't expecting such responses. I thought this was an easy fix and I was the dumby that couldn't figure it out. Thanks again for all the advice.

Mike, I'm going to try again this Saturday after my son's soccer game. If I'm successfull I'll let you know if the new sensor helped improve my mileage and/or irritating idle. The sensor looks like it's the original which would have about 110k miles on it. So, it's over due to replace.

Thanks again...Ron

Rick Lee · Rick Lee's Garage

I got lucky and was able to get my old sensor out with a crescent wrench while holding the cat between my knees. That clip should pop right off and you should be able to get a box or flare wrench aorund the base of the sensor, grab a breaker bar and have at it - all this once you've removed the wheel, of course. Spray some Liquid Wrench on there the night before.

bob hodges · 09-25-2003, 04:49 AM

Fred/ Richard,

I will give it a try after running the engine. Thanks for the tip.

Bob

fitz · fitz's Garage

Well, after all your advice I got the little heat shield off the sensor. I tried using a cresent wrench and that didn't work. Then I looked for a deep socket but the sensor was still to tall. Finally, I went back to the sensor tool/socket I bought from Pelican and a long pole over the rachet handle and it came loose. Ten minutes after removing the old sensor I had the new one on and was putting the tire back on the car.

The car still rocks a little at stop lights but it seems the gas mileage is coming up. It also seems as though the engine is running a little quieter. I'm going to Fresno tomorrow, so I'll have a better chance of evaluating the gas mileage.

Thanks again for the help....Ron Fitz

tt_targa · 10-09-2003, 09:36 AM

I have had a rough idle issue with my '83 targa. The voltages on the O2 sensor looked good so I started looking elseware.

The 15 deg temp swith would only get down to 180 ohms so I suspected this was a problem. When I grounded the wire, the system went to a leaner closed loop operation and the idle smoothed out.

I had the passenger seat out so it was easy the ground the sensor there and also test the performance of the other sensors.

Good Luck